The invention relates to a production of cores for electromechanical devices such as motors, and more particularly the production of such cores by stacking of a plurality of laminations.
It is known to produce cores for electromechanical devices such as motors by stacking a plurality of laminations to form stators and matching rotors. Frequently, when forming the rotors or stators by a series of stacked laminations, the laminations are maintained in a loose configuration in a very long stack, thus allowing the motor manufacturer to select a plurality of loose laminations from one end of the stack to form a final stack of a given height for a particular motor application.
It is also known in lamination stacking dies which create finished stacks of a predetermined height to provide a rotatable chamber where the rotors or stators are blanked out so that the laminations of a rotor can be xe2x80x9cindexedxe2x80x9d. Indexing typically refers to one or more of the laminations being rotated by a prescribed angle such as 90 or 180xc2x0 so that a varying thickness of the steel strip from which the rotors or stators are punched out does not result in a stack having a tilt, that is where one side is higher than the other. By rotating one or more laminations, the stack can be evened out since the indexing will compensate for the varying strip thickness from one side of the strip to the other.
Typically, such indexed lamination stacks are produced in stacking dies where a prescribed stack having a given number of laminations or for a given height is produced. However, in the production of loose laminations wherein no particular given stack height is provided, a difficulty arises in indexing such loose laminations for the following reasons.
High volume production of loose laminations requires the use of a chute attached to the bottom of a die bolster plate in which the laminations travel through after being blanked from the die. Due to the weight of the laminations in the chute, backpressure is created. To keep the chute backpressure from forcing the blank laminations back up through the die opening, xe2x80x9cpinchxe2x80x9d or xe2x80x9cchokexe2x80x9d rings are installed in the die. In order to combine loose lamination indexing with part removal by chutes, a separation must be made between the laminations in the indexing chamber and those in the chute to prevent lamination damage from occurring as the index chamber rotates.
It is an object of the present invention to provide a separation as described above so that loose laminations can be successfully rotationally indexed without causing lamination damage.
According to the present invention, a system and method is provided for rotating one or more laminations relative to other laminations in a loose lamination die. In a punching station for punching laminations free from a strip, a rotatable chamber is provided. As the punch engages the strip, the rotatable chamber is pushed downwardly. After the lamination has been punched, and as the punch moves upwardly, the rotatable chamber returns to its original upward position. In the upward position, a gap results between laminations retained at the bottom end of the rotatable chamber and laminations just below the bottom of the rotatable chamber. Because of the gap, the rotatable chamber can then be rotated without causing damage to the lamination at the bottom of the rotatable chamber and the lamination just below the rotatable chamber.